1. Field of the Invention
The invention relates to a belt conveyor whose frame comprises a gas cabinet, the belt being conveyed with both parts over a trough bottom, said trough bottoms forming part of said gas cabinet and being provided with apertures, while one or more compressors are provided to take a gas such as air through the apertures in the trough bottoms until it is underneath said belt parts to carry them, said gas cabinet having a partition above the bottom part and under the trough bottom for the top part used for the conveyance of material and goods, in order to divide the cabinet into two separate gas chambers, while a compressor is connected by the suction side to the bottom gas chamber.
2. Description of the Related Art
Such a conveyor is known from U.S. Pat. No. 3,734,271. Here the conveyor is completely enclosed by an encasing. The compressor first forces the air under the bearing top part of the belt and then under the returning bottom part, so that it is forced in a closed circuit in series along the bottom of the belt parts. For this, the air leaving the side edges of the bearing part of the belt is collected by the encasing and conveyed to the cabinet part underneath the returning part. The compressor draws in from the chamber in the cabinet above the returning part. A through-running, broad slit is provided in the trough bottom of said returning part.
Such a design has a number of disadvantages. The encasing, also intended to prevent dust being produced in the surroundings, makes the design expensive and the returning part of the belt difficult to reach for repair and maintenance purposes. Good accessibility is, however, necessary because with almost all types of bulk goods particles thereof adhere to the bottom part and can remain in the cabinet part and accumulate there, so that this cabinet part will have to be cleaned at regular intervals. For this, the bottom side of the encasing and the bottom side of the air cabinet have to be detached. Depending on the type of bulk goods, this will have to be carried out, e.g. weekly or monthly, so that the time-consuming removal and refitting in airtight fashion of the various parts can mean an unacceptably high cost item, particularly in the case of conveyors which are several dozen meters long or more.
This known conveyor also has the major disadvantage that the trough bottom of the bottom part is provided with a broad slit running along the entire length, serving as a passage for the flowing gas underneath the bottom part. The slit is approximately 0.3 times the width of the belt. The wide passage for the gas, formed by the broad slit in the trough bottom of the returning part, means that with lateral connection of the compressor to the cabinet, in which the returning part is located, said part will be pressed upwardly much higher at the side of said connection than at the other side, and the gas in seeking the route of least resistance will flow in large quantities near such a compressor connection, and to a much lesser degree or not at all at greater distances from it. In the case of longer belts it is therefore necessary to use many compressors, and the returning part will be pressed up too high in some places and in the process can touch fixed parts of the cabinet and at other points rub over its trough bottom, and that part will become unstable, vibrate and flap up and down, in which case the whole structure can be subject to adverse and troublesome vibrations, and belt wear and energy consumption are unnecessarily high.
The object of the invention is to produce an improvement in this situation, so that a conveyor of simple design is obtained with a returning part which is carried uniformly by a gas film and operates stably without unnecessary energy being used, and is easily accessible for repair and maintenance work, such as periodic cleaning of the bottom cabinet part to remove the dust and grit which has collected in it and which has been brought in by the returning part.